Aromatic polycarbonates are employed in numerous technical fields of application because of their typical tough and elastic properties. A disadvantage is their poor mold release when injection-molded which frequently results in relatively long cycle times. However, for economic and technical reasons it is desirable to shorten the cycle times as far as possible so as to manufacture larger numbers of moldings per unit time on the injection molding machines. This can be achieved, for example, by injection molding at higher temperatures. However, for this purpose the polycarbonate melt must be so modified that the release of the molding from the mold wall takes place with low release forces and at high temperatures without sticking of the solidified melt to the mold wall. Easy mold release at high temperatures is in particular also desired in the case of complicated moldings which are produced in molds with parts which cannot be cooled (for example cross-webs, cores and the like).
In the past, long-chain aliphatic carboxylic acid esters of monohydric and trihydric alcohols have been added to improve the mold release of aromatic polycarbonates in accordance with DOS (German Published Specification) NO. 2,064,095, DOS (German Published Specification) No. 2,220,185, U.S. Pat. No. 3,784,595 and U.S. Pat. No. 3,836,499. However, a disadvantage of these mold release agents is the deterioration of the mechanical properties of the aromatic polycarbonates on prolonged heat exposure as a result of which the aromatic polycarbonates which have been modified according to DOS (German Published Specification) No. 2,064,095 and DOS (German Published Specification) No. 2,220,185, U.S. Pat. Nos. 3,784,595 and 3,836,499 in order to give easy mold release no longer satisfy certain technical requirements.
U.S. Pat. No. 3,775,367 discloses the use of specific perfluoroalkanesulphonic acid derivatives as additives to polycarbonates to improve the flame resistance of polycarbonates, but makes no mention of the mold release properties of the additives.